I. Field of the Invention
The invention relates generally to rotary lawn mowers, and more particularly, to rotary lawn mowers having blade mountings which permit selective displacement of the blades between a retracted and an extended position.
II. Description of the Prior Art
Rotary lawn mowers which include blade housings in which the blades are movable between a retracted and an extended position are known and disclosed in the following U.S. Patents:
Kontis U.S. Pat. No. 2,939,264 June 7, 1960 PA0 Tatum U.S. Pat. No. 3,133,398 May 9, 1964 PA0 Harloff U.S. Pat. No. 3,184,907 May 25, 1965 PA0 Kirk U.S. Pat. No. 3,320,732 May 23, 1967 PA0 Wood U.S. Pat. No. 3,690,051 Sept. 12, 1972 PA0 Goserud U.S. Pat. No. 3,715,874 Feb. 13, 1973 PA0 Spear U.S. Pat. No. 3,715,874 June 12, 1973 PA0 Morris U.S. Pat. No. 4,114,354 Sept. 19, 1978 PA0 German Pat. Nos. 1,582,345; 1,582,352; 2,058,347; and 2,327,356 PA0 Russian Pat. No. 246,184 PA0 French Pat. No. 1,519,808 PA0 Australian Pat. No. 246,599
Attention is also directed to the following foreign patents:
It is desirable for the operator of a lawn mower to be able to selectively control the disposition of the movable cutting blades so that the cutting blades are in their extended position when the operator is in guiding control of the lawn mower. Much of the above cited prior art (in particular, Kontis, Kirk, Wood, Goserud, Spear, Morris and the Russian Patent) coordinate the disposition of the movable cutting blades with the engine speed, such that the cutting blades move into the extended position in response to a predetermined amount of centrifugal force. None of the above cited prior art discloses a blade control mechanism for selectively controlling the disposition of the cutting blades regardless of the engine speed or amount of centrifugal force present, and which control mechanism returns the cutting blades to their retracted position whenever the operator is not in guiding control of the lawn mower. Furthermore, none discloses a means for swirling the air within the chassis to provide for effective airborne discharge of grass clippings, particularly when the cutting blades are in their retracted position.